Growth mechanisms and origin of localized surface plasmon resonance coupled exciton effects in Cu_2-xS thin films

We have demonstrated a robust protocol to prepare Cu_2-xS thin films with a controlled crystal phase and size which exhibit localized surface plasmon resonance (LSPR) coupled exciton effects by a simple template free single step wet chemical method without any surfactant. The LSPR frequency can be tuned in the Cu_2-xS thin films by the growth temperature and time which controls the free carrier density. These selectively grown Cu_2-xS thin films possess a tunable band gap (2.6-1.4 eV) due to the quantum size effect. The origin of the LSPR coupled exciton effects are discussed.